The present invention relates to an apparatus for analyzing a liquid sample for use in the chemical field and the biochemistry field, and more particularly to an apparatus for performing pretreatment, such as washing of a needle or dilution of the collected sample.
For example, analysis of glycated hemoglobin using, for example, liquid chromatography has been performed such that a blood sample in a tube (a vacuum blood collecting tube) having a rubber cap is collected in a predetermined quantity to analyze the quantity of glycated hemoglobin component in the sample.
The foregoing operation is specifically performed such that a pin type needle capable of penetrating the rubber cap of the vacuum blood collecting tube is caused to accurately penetrate a penetration target portion having a diameter of about 5 mm in the central portion of the rubber cap to collect a blood sample in a predetermined quantity, and then the blood sample is diluted into an arbitrary dilution ratio, followed by introducing the blood sample into an analysis column. Therefore, pretreatment including collection (sampling) and dilution must be performed before the sample is actually supplied to the column. When analysis of glycated hemoglobin is performed, another pretreatment for hemolyzing red blood cells must be performed before the sample is supplied to the analyzing column. To sequentially analyze a plurality of blood samples, pretreatment of washing the needle must be performed before the operation is performed.
As described above, various analyzing apparatuses including the glycated-hemoglobin analyzing apparatus, have the structure to control the component parts thereof to cause the components parts to perform complicated operations. Moreover, special parts for washing and dilution have been provided.
The pretreatment will now be described with reference to FIG. 1 such that an apparatus for analyzing blood, such as the glycated-hemoglobin analyzing apparatus, is taken for example. The glycated-hemoglobin analyzing apparatus is required to be capable of sucking the blood sample from the vacuum blood collecting tube having the rubber cap with satisfactory reproducibility, removing contamination occurring due to carrying of the sample and having excellent dilution reproducibility about, in general, 200 times to about 400 times.
Initially, a needle 1 is moved to a sampling position 2, and then a rubber cap is caused to penetrate a vacuum blood collecting tube 3 having the rubber cap to be moved downwards. Thus, a blood sample is sucked in a predetermined quantity attributable to the reciprocating operation of a first syringe 4. To suck the blood sample with satisfactory reproducibility, the foregoing predetermined quantity must be 3 microliter or greater. In order to cause the first syringe 4 to perform the sucking operation, a first valve 5 is closed.
Then, the needle is moved to a dilution tank 6 to discharge the sucked blood sample, and then a second syringe 7 is operated to jet out solution (diluting solution) from a dilution nozzle 8 in a predetermined quantity so as to dilute the blood sample to a predetermined dilution ratio (in general, 200 times to 400 times). After jetting of the solution from the dilution nozzle 8 has been completed, the first valve and the second valve 9 are switched to introduce the diluted sample into a sample injector 10 formed by using a hexagonal valve. Then, the diluted sample is supplied to the analyzing column. To also perform the dilution operation with excellent reproducibility, the quantity of the collected blood sample must be 3 microliter or greater.
After the foregoing operations have been completed, the dilution chamber and the needle are washed in order to analyze a new blood sample. The needle is washed by a method in which solution is allowed to flow in a needle washing block 11 by a washing pump 12 or a method in which washing solution is discharged from the needle in a needle washing tank 13, and then a third valve 14 is opened and a suction pump 15 is operated so as to suck the contaminated washing solution into a vacuum chamber 16 followed by opening a fourth valve 17 at a certain timing so as to discharge the contaminated solution into a discharge portion 18.
The dilution tank 6 is washed such that the washing solution is discharged from the needle 1 or the dilution nozzle 8 into the dilution tank until the tank is fully filled with the solution. Then, a fifth valve 19 is opened, and then the suction pump 15 is operated so as to suck the contaminated washing solution into the vacuum chamber 16, followed by opening the fourth valve 17 at a certain timing so as to discharge the contaminated solution into the discharge portion 18.
To reduce the contamination occurring between the samples, the needle 1, the needle washing tank 13, the needle washing block 11, the dilution tank 6, the sample injector 10 and the inside portions of the pipes for establishing the connections among foregoing components must be washed.
The glycated-hemoglobin analyzing apparatus and the like, and particularly, the conventional analyzing apparatus for treating liquid samples, such as blood samples, must suck the blood sample from the vacuum blood collecting tube in a quantity of 3 microliter or more in order to improve the reproducibility. Since the dilution ratio of a usual blood sample is 200 times to 400 times, the capacity of the dilution tank must be 1500 microliter or greater. As a result, there arises a problem in that a large quantity of washing solution not smaller than about 3000 microliter is required to perform the washing operation.
Moreover, the conventional apparatus must be provided with the exclusive suction pump and the exclusive valve for washing the dilution tank. Moreover, the exclusive solution supply pump and an exclusive valve are required to wash the needle. As a result, the structure of the apparatus becomes too complicated and operation of each component becomes too complicated. As a result, a long time is required to perform the pretreatment.
The conventional apparatus shown in FIG. 1 involves the structure such that the dilution tank 6 is fully filled with the washing solution discharged from the needle 1 or the dilution nozzle 8 followed by opening the fifth valve 19 to perform sucking. Therefore, the upper end portion of the dilution tank cannot be washed sufficiently and thus the probability of the occurrence of contamination cannot be eliminated. According to circumstances, there arises a problem in that the needle or the valve is clogged. Therefore, complicated maintenance must be performed such that the dilution tank 6, the valve 19 and the suction pump 15 must periodically removed from the apparatus so as to be manually washed.
In particular, in the case of the vacuum blood collecting tube having the rubber cap, the needle penetrates the rubber cap. Therefore, there is a possibility that abrasion dust of the rubber cap allowed to adhere to the needle scatters into the apparatus. In this case, there arises a problem in that the overall passage, which reaches the analyzing column, is clogged.
After the liquid sample has been sucked, the needle is moved into the dilution tank, and then the diluting solution is discharged from the dilution nozzle to realize an arbitrary dilution ratio (200 times to 400 times). At this time, the diluting solution is jetted out into the dilution tank from a diagonally upward direction deviated from the center of the dilution tank so as to generate a swirl in the dilution tank in order to improve the dilution efficiency. However, since the quantity of the jetted diluting solution is determined by the solution ratio, there arises a problem in that the blood sample and the diluting solution cannot sufficiently be mixed if the solution ratio is low.
If a liquid sample is a sample of blood, the pretreatment sometimes includes the operation for hemolyzing blood in addition to the dilution operation. However, only the foregoing dilution operation easily results in unsatisfactory degree of the hemolysis.